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DTSTART:20260329T030000
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DTSTAMP:20260614T113051Z
UID:1783076400@ist.ac.at
DTSTART:20260703T130000
DTEND:20260703T140000
DESCRIPTION:Speaker: Xin Tong\nhosted by Carl Goodrich\nAbstract: Embryo cl
 eavage — a series of rapid\, reductive cell divisions — is the first m
 orphogenetic movement following fertilisation. It lays the foundation for 
 subsequent developmental events\, including gastrulation\, germ layer spec
 ification\, organogenesis\, and the establishment of the overall body plan
 . Two major modes of cleavage exist in the animal kingdom: holoblastic (co
 mplete) and meroblastic (incomplete) cleavage. Because holoblastic cleavag
 e resembles canonical cytokinesis\, its biochemical and mechanical basis h
 as been extensively studied — an annular contractile ring forms at the e
 quator and constricts in a purse-string-like manner\, leading to the compl
 ete separation of two daughter cells. In contrast\, although meroblastic c
 leavage occurs widely across the animal kingdom (e.g. in fish\, reptiles\,
  birds\, and cephalopod molluscs)\, its mechanical basis remains largely u
 nclear. During meroblastic cleavage\, the cytokinetic furrow forms only at
  one pole and does not traverse the entire embryo\, raising the question o
 f how cytokinesis proceeds in the absence of a closed contractile ring. Mo
 reover\, the resulting daughter cells are not fully separated from the und
 erlying yolk compartment\, and how these blastomeres are subsequently cell
 ularised remains unknown. This thesis takes the zebrafish as a model organ
 ism to address both questions. The first part characterises the biochemica
 l and mechanical mechanisms underlying non-canonical meroblastic cleavage\
 , revealing a two-phase process in which actomyosin cable contraction and 
 cadherin-mediated membrane adhesion act sequentially to drive furrow ingre
 ssion and invagination. The second part sheds light on the spatiotemporal 
 dynamics by which individual blastomeres become cellularised\, and uncover
 s a previously unrecognised contribution of central blastomeres to the yol
 k syncytial layer.
LOCATION:Central Bldg / O1 / Mondi 3 (I01.O1.010) \, ISTA
ORGANIZER:
SUMMARY:Xin Tong: Thesis Defense: Towards a deeper understanding of merobla
 stic cleavage - biochemical mechanisms of partial cytokinesis and cellular
 ization in zebrafish embryogenesis
URL:https://talks-calendar.ista.ac.at/events/6519
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